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Vitali F. Nesterenko

Publications and source records attributed to Vitali F. Nesterenko.

9 recordsLinked to original sources
arXiv2026

Non-solitary wave response generated by "soft" striker impact on strongly nonlinear weakly dissipative granular chains

It is well known that striker impact on strongly nonlinear, non-dissipative or weakly dissipative granular chains assembled from spheres (or cylinders with flat ends and spheres) having similar masses results in strongly nonlinear Nesterenko solitary waves on a very short distance from the impacted end. This paper presents the first experimental results on the nature of the wave response excited by striker impact on strongly nonlinear weakly dissipative discrete chains assembled from cylinders with flat ends and spheres having similar masses depending on the ramp time of the incoming pulse. Variation of the pulse ramp time was accomplished using "hard" and "soft" striker impact. In the case of "hard" impact, the incoming pulse with relatively short ramp time was split into Nesterenko solitary waves after traveling about 20 particles as in previous publications. The "soft" impact by the same striker with the same velocity was achieved by placing a small mass PTFE spherical particle inside a PTFE O-ring at the top of the first cylinder resulting in significantly longer ramp time of incoming pulse. The incoming pulse generated by "soft" impact did not split into a train of solitary waves despite the initial steepening of the leading front due to strong nonlinearity. Instead, it traveled as a shock-like stress wave a long distance of 131 particles. Thus, the generation of a train of solitary waves or shock-like stress wave in a weakly dissipative, strongly nonlinear discrete chain depends on the duration of the incoming pulse ramp. Ramping incoming pulse resulted in dramatic decrease of shock-like stress wave amplitude in comparison with amplitude of the leading solitary wave in case of "hard" impact.

nlin.PS↗
arXiv2015

Nature of short high amplitude pulses in a periodic dissipative laminate metamaterial

We study the evolution of high amplitude stress pulses in periodic dissipative laminates taking into account the nonlinear constitutive equations of the components and their dissipative behavior. Aluminum and Tungsten laminate was taken as an example due to the large difference in acoustic impedances of aluminum and tungsten, the significant nonlinearity of aluminum constitutive equation at the investigated range of stresses, and its possible practical applications. Laminates with different cell size, which controls internal time scale, impacted by the plates with different thicknesses, determining the incoming pulse duration, were investigated. It has been observed that the ratio of the duration of the incoming pulse to the internal characteristic time determines the nature of the high amplitude dissipative propagating waves, the oscillatory shock like profile, the train of localized pulses or a single localized pulse. These localized quasistationary waves resemble solitary waves even in the presence of dissipation: the similar pulses emerged from different initial conditions, indicating that they are inherent properties of the corresponding laminates, their characteristic length scale is determined by the mesostructural scale and the stress amplitude, and they mostly recover their shapes after collision with phase shift and a linear relationship exists between their speed and amplitude. A theoretical description approximating the shape, length scale and speed of these high amplitude dissipative pulses was proposed based on the Korteweg de Vries type equation with a dispersive term dictated by the mesostructure. The nonlinear term is derived from nonlinear constitutive equations of Aluminum and Tungsten, which were extracted from their Hugoniot curves.

cond-mat.mtrl-sci↗
arXiv2014

Multiscale tunability of solitary wave dynamics in tensegrity metamaterials

A new class of strongly nonlinear metamaterials based on tensegrity concepts is proposed and the solitary wave dynamics under impact loading is investigated. Such systems can be tuned into elastic hardening or elastic softening regimes by adjusting local and global prestress. In the softening regime these metamaterials are able to transform initially compression pulse into a solitary rarefaction wave followed by oscillatory tail with progressively decreasing amplitude. Interaction of a compression solitary pulse with an interface between elastically hardening and softening materials having correspondingly low-high acoustic impedances demonstrates anomalous behavior: a train of reflected compression solitary waves in the low impedance material; and a transmitted solitary rarefaction wave with oscillatory tail in high impedance material. The interaction of a rarefaction solitary wave with an interface between elastically softening and elastically hardening materials with high-low impedances also demonstrates anomalous behavior: a reflected solitary rarefaction wave with oscillatory tail in the high impedance branch; and a delayed train of transmitted compression solitary pulses in the low impedance branch. These anomalous impact transformation properties may allow for the design of ultimate impact mitigation devices without relying on energy dissipation.

cond-mat.mtrl-sci↗
arXiv2008

Short Pulse Dynamics in Strongly Nonlinear Dissipative Granular Chains

We study the energy decay properties of a pulse propagating in a strongly nonlinear granular chain with damping proportional to the relative velocity of the grains. We observe a wave disturbance that at low viscosities consists of two parts exhibiting two entirely different time scales of dissipation. One part is an attenuating solitary wave, is dominated by discreteness and nonlinearity effects as in a dissipationless chain, and has the shorter lifetime. The other is a purely dissipative shocklike structure with a much longer lifetime and exists only in the presence of dissipation. The range of viscosities and initial configurations that lead to this complex wave disturbance are explored.

cond-mat.soft↗
arXiv2007

High Strain and Strain-Rate Behaviour of PTFE/Aluminium/Tungsten Mixtures

Conventional drop-weight techniques were modified to accommodate low-amplitude force transducer signals from low-strength, cold isostatically pressed 'heavy' composites of polytetrafluoroethylene, aluminum and tungsten. The failure strength, strain and the post-critical behavior of failed samples were measured for samples of different porosity and tungsten grain size. Unusual phenomenon of significantly higher strength (55 MPa) of porous composites (density 5.9 g/cc) with small W particles (less than 1 micron) in comparison with strength (32 MPa) of dense composites (7.1 g/cc) with larger W particles (44 microns) at the same volume content of components was observed. This is attributed to force chains created by a network of small W particles. Interrupted tests at different levels of strain revealed the mechanisms of fracture under dynamic compression.

cond-mat.soft↗
arXiv2007

Shock (Blast) Mitigation by "Soft" Condensed Matter

It is a common point that "soft" condensed matter (like granular materials or foams) can reduce damage caused by impact or explosion. It is attributed to their ability to absorb significant energy. This is certainly the case for a quasistatic type of deformation at low velocity of impact where such materials are widely used for packing of fragile devices. At the same time a mitigation of blast phenomena must take into account shock wave properties of "soft" matter which very often exhibit highly nonlinear, highly heterogeneous and dissipative behavior. This paper considers applications of "soft" condensed matter for blast mitigation using simplified approach, presents analysis of some anomalous effects and suggestions for future research in this exciting area.

cond-mat.soft↗
arXiv2006

Observation of two-wave structure in strongly nonlinear dissipative granular chains

In a strongly nonlinear viscous granular chain under conditions of loading that exclude stationary waves (e.g., impact by a single grain) we observe a pulse that consists of two interconnected but distinct parts. One is a leading narrow "primary pulse" with properties similar to a solitary wave in a "sonic vacuum." It arises from strong nonlinearity and discreteness in the absence of dissipation, but now decays due to viscosity. The other is a broad, much more persistent shock-like "secondary pulse" trailing the primary pulse and caused by viscous dissipation. The medium behind the primary pulse is transformed from a "sonic vacuum" to a medium with finite sound speed. When the rapidly decaying primary pulse dies, the secondary pulse continues to propagate in the "sonic vacuum," with an oscillatory front if the viscosity is relatively small, until its eventual (but very slow) disintegration. Beyond a critical viscosity there is no separation of the two pulses, and the dissipation and nonlinearity dominate the shock-like attenuating pulse which now exhibits a nonoscillatory front.

cond-mat.soft↗
arXiv2002

Bulk Magnesium Diboride, Mechanical and Superconducting Properties

Hot Isostatic Pressing was applied to synthesize bulk samples with diameter up to 30 mm starting with Alfa Aesar magnesium diboride powder. HIPing at 2 kbar, 1000 C with cooling under pressure (DMCUP cycle) resulted in a fully dense (or low porosity) material with a sharp superconducting transition and critical current comparable with the best reported. Elastic constants were measured using method of resonant ultrasound spectroscopy. Their values for most dense samples (bulk modulus 142.5 GPa and Young's modulus 272.5 GPa) are close to theoretically predicted values for solid magnesium diboride. Porosity is resposible for lower values of elastic constants. Fracture toughness is evaluated based on measurements of microhardness and elastic constants. Upper critical field and irreversibility field are comparable with data for samples sintered at 3 GPa. Microstructural propeties of HIPed smaples are responsible for enhanced flux pinning. Method allows scaling of the size of the samples and manufacture of complex shapes.

cond-mat.supr-con↗